Synthetic lubricants



Patented Mar. 14, 1950 SYNTHETIC LUBRICANTS Harry G. Doherty and Alexander N. Sachanen, Woodbury, and Francis M. Seger, Pitman, N. J., assignors to Socony-Vacuum Oil Company, Incorporated, a corporation of New York No Drawing. Application February 6, 1948, Serial No. 6,814

14 Claims.

This invention relates, broadly, to new synthetic lubricants having a desirable combination of properties, namely, high viscosity index, relatively low pour point, and satisfactory stability; and to a process for their preparation. It is more particularly concerned with the proparation of these lubricants by the thermal, non-catalytic treatment of certain types of normally liquid olefins at cracking temperatures.

Polymerization and condensation reactions in general have long been accomplished by the use of either heat or catalysts, orboth. Olefms have been catalytically polymerized to form oils, and it. is known that ethylene can be thermally polymerized by heat alone to form an oil.

In a copending application, Serial Number 761,716, died on July 17, 1947 and now abandoned, in which the inventors are two of those in the present application, a process has been disclosed for the preparation of synthetic lubricants. By this process, normal, alpha-monoolefins having from about six to about twelve carbon atoms per molecule are thermally and non-catalytically converted into lubricants having high viscosity indices and low pour points. The conditions employed in the process of this copending application include temperatures falling within the range varying between about 500 F. and about 750 F., and preferably, between about 600 F. and about 700 F.

Although good yields of synthetic lubricants have been obtained by treating normal, alpha monoolefins having between about six and about twelve carbon atoms per molecule at temperatures lower than about 700 F., in the absence of catalytic material, the residence time obviously required to produce commercially feasible yields is inordinately long. However, as has been disclosed in copending application, Serial Number 761,716, mentioned hereinbefore, when temperatures higher than about 700 F. are employed in the operation involving normal, alpha-monoolefins having between about six and about twelve carbon atoms per molecule, the yields of synthetic lubricant begin to diminish. As indicated in the copending application referred to, at temperatures above about 700 F., the yields of synthetic lubricants are too low to be commercially feasible, regardless of the time of reaction.

In accordance with the present invention, it has been discovered that synthetic lubricants possessing the combination of desirable properties referred to hereinbefore, can be produced in good yields and in a relatively short period of tme between about six and about fourteen carbon atoms per molecule, in the absence of catalytic material, at temperatures higher than about 700 F. This is achieved by carrying out the operation in a gaseous atmosphere of hydrogen, carbon monoxide, or mixtures of the two gases.

Accordingly, it is an object of the present invention to produce synthetic lubricants possessing high viscosity indices, low pour points, and good stability. An important object is to provide a process for producing said lubricants from normal, alpha-monoolefins having between about six and about fourteen carbon atoms per molecule by subjecting them to a non-catalytic treatment at temperatures higher than about 700 F. A more specific object is to provide a process for producing valuable synthetic lubricants from normal, alpha-monoolefins having between about six and about fourteen carbon atoms per molecule in good yields and using relatively short reaction times. Other objects and advantages of the present invention will become apparent to those skilled in the art from the following description.

Broadly stated, the present invention provides synthetic lubricants possessing high viscosity indices, low pour points and good stability, and a process for producing the same, which comprises passing normal, alpha-monooleflns having between about six and about fourteen carbon atoms per molecule into a reaction zone, in the absence of catalytic material, at a temperature falling within the range varying from about 700 F, to about 900 F., in the presence of hydrogen, carbon monoxide, or mixtures of the two gases, the partial pressure of said gas or mixture of gases falling within the range varying from about pounds per square inch to about 5000 pounds per square inch.

Suitable olefinic charge stocks for the process of making the synthetic lubricants contemplated herein com rise the normally-liquid, normal, alpha-monoolefins containing between about six and about fourteen carbon atoms per molecule. Normal, alpha-monoolefins containing from about eight to about twelve carbon atoms per molecule are preferred. It must be clearly understood that these oleflns are characterized by a normal carbon chain configuration and by a single double bond in the alpha position on the carbon chain. Non-limiting examples of the olefinic reactant are l-hexene, l-octene, 1-decene,-

3 the limits mentioned hereinbei'ore. In both of the aforementioned mixtures, it is to be understood that the relative amounts of desired normal.

alpha-monoolefins is dictated solely by commercial considerations. For example, there may be a large amount of parafllnic hydrocarbon material in such mixtures, but, in mixtures relatively poor in olefinic reactants, excessive amounts of charge stock would have to be treated in order to obtain significant yields of des red synthetic lubricants. In practice, it is preferred that such mixtures contain at least fifty per cent of olefinic reactant by weight.

Suitable charge stocks may be obtained from many sources. such as, for example, the liquid olefinic materials obtained by cracking of paraffin wax, slack wax, gas oils, foots oils, heavy petroleum residua, etc. A particularly good source of mixed olefinic reactants is the modified Fischer- Tropsch process. In this connection, it should be mentioned that it issuspected that substantially straight-chain, aloha-monoolefins having between about six and about fourteen carbon atoms per molecule, i. e., alpha-mononleflns whichcontain one or more side chains which are very short relative to the main chain length, will produce products having properties closely approximating those of the products contemplated herein. For example, should the methyl-l-nonene; become available, it is suspected that they would produce synthetic lubricants substantially equivalent to those produced from the corresponding normal, alpha-monoolefin.

Essenti lly pure hydrogen and carbon monoxide which are utilized in the process of the present invention are available commercially. Purity of the gases, however, is not an important factor. Mixtures of gases which comprise predominantly hydrogen and/or carbon monoxide may be used, for example, hydrogen-rich refinery gases, synthesis gases, and gases obtained by the oxygen-deficient combustion of fuel oil, coal, etc. In practice, it is preferred to use mixtures of hydrogen and carbon monoxide for the process of the present invention. The volume ratio of hydrogen to carbon monoxide varies, preferably, between 10:1 and 1:1, respectively.

The-partial pressure of the gas, or mixture of gases employed in the process of the present invention' must fall within the range varying from about 50 pounds per square inch'to about 5000 pounds per square inch. In practice, partial pressures falling within the range varying from about 50 pounds per square inch to about 2500 pounds per square inch are preferred.

Inasmuch as the present invention is predicated in part uoon the use of temperatures higher than about 700 F., the reaction temperature utilized is a critical factor. The present process is carried out at temperatures falling within the range varying from about 700 F. to about 900 F. In practice, it is preferred, however, to operate at a temperature falling within the range varying from about 700 F. to about 800 F. When temperatures lower than about 700 F. are employed, there is no great advantage over the process described in the copending application referred to hereinbefore.

The time of reaction varies inversely with the reaction temperature. As stated hereinbefore, the process of the present invention is operated at temperatures higher than about 700 F. in order to produce synthetic lubricants from normal, alpha-monoolefins having between about six and about fourteen carbon atoms per molecule in good yields and in relatively short reaction times. Accordingly, the reaction time varies between about .one hour and about ten hours. In practice, how- 5 ever, the time of reaction usually varies between about one hour and about three hours, depending on the reaction temperature employed.

The total pressure in the reaction zone is not too critical a factor. Pressures greater than about 100 pounds per square inch may be employed. In practice, the total reaction pressure is usually greater than about 500 pounds per square inch.

The liquid eilluent from the reaction zone will comprise some unreacted olefinic material. an intermediate-boiling polymer, and the desired synthetic lubricant. The synthetic lubricant may be recovered by distilling off the unreacted olefinic material which can be recycled to the process, if

desired, and the intermediate-boiling polymer. In practice, this is accomplished by removing all olefinic reactant and intermediate-boiling material which will distill at a pot temperature of about 210 C. under a pressure of about three millimeters of mercury.

In the examples set forth hereinafter, the process is carried out in a sealed, rocking-type, stainless steel bomb. However, any suitable reactor equipped for providing adequate heat transfer and built to withstand relatively high pressures, may be utilized in the operation of the process. The operation may be carried out as a batch process, or as a continuous process. In

the latter case, the unreacted olefinic reactant may be recycled for further treatment in the reaction zone.

The following specific examples illustrate the mode of preparing the synthetic lubricants by the process of the present invention, and the advantages of the process of the present invention. It is to be clearly understood that the invention is not to be limitedto the specific olefinic reactants or to the operations and manipulations described therein. As will be apparent to those skilled in the art, a wide variety of other olefinic reactants, as set forth hereinbefore, may be used to prepare the synthetic oils in accordance with this invention.

In a typical example, seven hundred grams of l-decene were charged into a bomb. The bomb head was secured and the reaction system was flushed several times with hydrogen or carbon monoxide or mixtures of the two to displace the air therefrom. Then more hydrogen gas or carbon monoxide'or mixtures of the two was introduced until a hydrogen or carbon monoxide or a mixture pressure of about 1000 pounds per square inch was obtained. Gentle rocking of the 00 bomb was commenced, and the reactants were cheated rapidly to about 750 F. This temperature was maintained for about three hours. At

the end of this period of time, heating and rocking were stopped. After the bomb had cooled, it was vented to relieve the pressure. The crude product was weighed, was transferred to a still,

and the unreacted olefinic charge and intermediate-boiling material were removed by distillation to a pot temperature of about 210 C. under a pressure of three millimeters of mercury. The residual oil was weighed and then was filtered through a thin bed of filtering clay to remove sediment and to clarify the 011.

For convenience, the pertinent data of each 7:; example are summarized in Table I.

TABLE I Thermal treatment of I-decm Example No 1 2 3 4 3 Gas Air H; CO H|+CO 1 N, Reaction Temp. F 750 748 750 750 760 Reaction Time, rs 3 3 3 3 3 Reaction Pressure, p. s. i. gang 1, 700 1, 250 2,100 300 Vacuum Distillate:

Wt. Per cent charge 40. 8 43. 3 38. 8 31. 5 56. 2 Spec c Gravity 0. 7771 0. 7707 0. 7649 0. 7649 0. 7079 Bromine Number 33. 4 37. b 44. 36. 2 40. 0 Synthetic Lubricant:

Yield. Wt. per cent charge 43 1 64. 3 39. 5 63. 3 30. 0 Viscosity, cs. 100 F 18.05 17. 22 13. 25 13.41 21.80 Viscosity. cs. 210 F 3. 79 3. 93 3. 24 3. 31 4. 29 Kinematic Viscosity Index 112. 2 145 127 134. 3 116. 4 Pour Point, F. +20 +20 +1) +10 Specific Gravity 0. 8602 0. 8348 0. 8433 0. 8333 0.8639 Bromine Number 21.2 15.8 20. 3 17. 3 Color, Lovibond 125 l. 0 8. 5 1

1 V. 1'. values above 140 are extrapolated irom tables. 400ib. CO and 6001b. Hz at 0.

Referring more particularly to Table I, it is apparent that good yields of oils having high viscosity indlces, relatively low pour points, and good color are obtained when normal, alphamonoolefins having between about six and about fourteen carbon atoms per molecule are treated at temperatures above about 700 F. in the presence of hydrogen, carbon monoxide, or mixtures of the two gases. Air (Example 1) is not efi'ective in the process (note color in particular). The reaction temperatures vary over a wide range, the shorter reaction times being required at higher temperatures. Pressures vary over a wide range, but they do not appear to seriously affect the yields or characteristics of the products. It is to be noted, furthermore, that the vacuum distillates, comprising unreacted olefinic charge and intermediate-boiling material, are sufllciently unsaturated to be profitably recycled to the process.

For the purpose of comparison, the yields 01' products prepared under varying conditions and in the presence of various gases are set forth in Table II, the data being obtained using decene-l and employing the procedure utilized in the examples given hereinbefore.

Obtained by dividing one unit weight of l-dccene charged by number of hours of reaction time.

I Obtained by dividing the weight [based on same unit of weight ased in (1)] of product obtained by'thc number of hours of reaction It is apparent that satisfactory products are obtained by the conversion of straight-chain, alpha-monoolefins at lower temperatures and for longer periods of time. However, the yield per hour under these conditions is lower than the yield per hour under the conditions of the present invention. This is of considerable practical importance due to the greatly increased production obtainable from a unit of a given size when operated under the conditions of this invention. It can also be seen that products of lower viscosity index are obtained when operating at 750 F.

- points, and good stability, which comprises:

thermally and non-catalytically heating a charge consisting essentially of a normal, alpha monoolefin having between about six and about fourteen carbcn atoms per molecule, at a temperature falling within the range varying from about 700 F. to about 900 F. for a period of time from about ten hours to about one hour, respectively, and in the presence of a gas selected from the group consisting of hydrogen, carbon monoxide, and mixtures of hydrogen and carbon monoxide,

' the partial pressure of said gas falling within the range varying from about 50 pounds per square inch to about 5000 pounds per square inch.

2. The method as defined by claim 1 wherein the charge consists essentially of hydrocarbons containing at least fifty per cent of said normal, alpha mono-olefin.

3. A process for the preparation of synthetic lubricants having high viscosity indlces, low pour points, and good stability, which comprises: thermally and non-catalytically heating a charge consisting essentially of a normal, alpha monoolefin having between about eight and about twelve carbon atoms per molecule, at a temperature falling within the range varying from about 700 F. to about 800 F. for a period of time from about ten hours to about one hour, respectively, and in the presence of carbon monoxide, the partial pressure of said gas falling within the range varying from about 50 pounds per square inch to about 2500 pounds per square inch.

4. A process for the preparation of synthetic lubricants having high viscosity indices, low pour points, and good stability, which comprises: thermally and non-catalytically heating a charge consisting essentially of a normal, alpha monoolefin having between about eight and about twelve carbon atoms per molecule, at a temperature falling within the range varying from about 700 F. to about 800 F. for a period of time from about ten hours to about one hour, respectively,

and in the presence or a mixture of hydrogen and carbon monoxide, the partial pressure 01' said gas falling within the range varying from about 50 pounds per square inch to about 2500 pounds per square inch.

5. A process for the preparation of synthetic lubricants having high viscosity indices, low pour points, and good stability, which comprises: thermally and non-catalytically heating a charge consisting essentially oi l-decene, at a temperature falling within the range varying from about 700 F. to about 800 F. for a period of time from about three 'hours to about one hour, respectively, and in the presence of hydrogen, the partial pressure 01' said gas falling within the range varying from about 50 pounds per square inch to about 2500 pounds per square inch.

6. A process for the preparation of synthetic lubricants having high viscosity indices, low pour points, and good stability, which comprises: thermally and non-catalytically heating a charge consisting essentially of l-decene, at a temperature falling within the range varying from about 700 F. to about 800 F. for a period of'time from about three hours to about one hour, respectively, and in the presence of carbon monoxide, the partial pressure of said gas falling within the range varying from about 50 pounds per square inch to about 2500 pounds per square inch.

7. A process for the preparation of synthetic lubricants having high viscosity indices, low pour points, and good stability, which comprises: thermally and non-catalytically heating a charge consisting essentially of l-decene, at a temperature falling within the range varying from about 700 F. to about 800 F. for a period of time from about three hours to about one hour, respectively, and in the presence of a mixture of hydrogen and carbon monoxide, the partial pressure of said gas falling within the range varying from about 50 pounds per square inch to about 2500 pounds per square inch.

8. The product obtained by the process for the preparation or synthetic lubricants having high viscosity indices, low pour points, and. good stability, which comprises: thermally and non-catalyticaily heating a charge consisting essentially of a normal, alpha mono-olefin having between about six and about fourteen carbon atoms per molecule, at a temperature falling within the range varying from about 700 F. to about 900 F. for a period of time from about ten hours to about one hour, respectively, and in the presence of a gas selected from the group consisting of hydrogen, carbon monoxide, and mixtures of hydrogen and carbon monoxide, thepartial pressure of said gas falling within the range varying from about'50 pounds per square inch to about 5000 pounds per square inch.

9. The product as defined by claim 8 wherein the charge consists. essentially of hydrocarbons containing at least fifty per cent of said normal, alpha mono-olefin.

10. The product obtained by the process for the preparation of synthetic lubricants having high viscosity indices, low pour points, and good stability, which comprises: thermally and noncatalytically heating a charge consisting essentially of a. normal, alpha mono-olefin having between about eight and about twelve carbon atoms per molecule, at atemperature falling within the range varying from about 700 F. to about 800 F. for a period of time from about ten hours to about one hour, respectively, and in the presence of carbon monoxide. the partial pressure of said gas 8 falling within the range varying from about 50 pounds per square inch to about 2500 pounds per square inch.

11. The product obtained by the process for the preparation oi! synthetic lubricants having high viscosity indices, low pour points, and good stability, which comprises: thermally and non-catalytically heating a charge consisting essentially of a normal, alpha mono-olefin having between about eight and about twelve carbon atoms per molecule, at a temperature falling within the range varying from about 700 F. to about 800 F. for a period of time from about ten hours to about one hour, respectively, and in the presence of a mixture of hydrogen and carbon monoxide, the partial pressure of said gas falling within the range varying from about 50 pounds per square inch to about 2500 pounds per square inch.

12. The product obtained by the process for the preparation of synthetic lubricants having high viscosity indices, low pour points, and good stability, which comprises: thermally and non-catalytically heating a charge consisting essentially of l-decene, at a temperature falling within the range varying from about 700 F. to about 800 F. for a period of time from about three hours to about one hour, respectively, and in the presence of hydrogen, the partial pressure of said gas falling within the range varying from about 50 pounds per square inch to about 2500 pounds per square inch. 1

13. The product obtained by the process for the preparation of synthetic lubricants having high viscosity indices, low pour points, and good stability, which comprises: thermally and non-catalytically heating a charge consisting essentially of l-decene, at a temperature falling within the range varying from about 700 F. to about 800 F. for a period of time from about three hours to about one hour, respectively, and in the presence 0! carbon monoxide, the partial pressure of said gas falling within the range varying from about 50 pounds per square inch to about 2500 pounds per square inch.

14. The product obtained by the process for the preparation of synthetic lubricants having high viscosity indices, low pour points, and good stability, which comprises: thermally and noncatalytically heating a charge consisting essentially of l-decene, at a temperature falling within the range varying from about 700 F. to about 800 F. for a period of time from about three hours to about one hour, respectively, and in the presence of a mixture of hydrogen and carbon monoxide, the partial pressure of said gas falling within the range varying from about 50 pounds per square inch to about 2500 pounds per square inch.

HARRY G. DOHERTY. ALEXANDER N. SACHANEN. FRANCIS M. SEGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,000,964 Lenher May 14, 1935 2,111,831 Batchelder et al. Mar. 22, 1938 2,315,080 Reid Mar. 30, 1943 OTHER REFERENCES 011 and Gas Journal, Mar. 28, 1935, pages 81, 82 and 96. 

1. A PROCESS FOR THE PREPARATION OF SYNTHETIC LUBRICANTS HAVING HIGH VISCOSITY INDICES, LOW POUR POINTS, AND GOOD STABILITY, WHICH COMPRISES: THERMALLY AND NON-CATALYTICALLY HEATING A CHARGE CONSISTING ESSENTIALLY OF A NORMAL, ALPHA MONOOLEFIN HAVING BETWEEN ABOUT SIX AND ABOUT FOURTEEN CARBON ATOMS PER MOLECULE, AT A TEMPERATURE FALLING WITHIN THE RANGE VARYING FROM ABOUT 700*F. TO ABOUT 900*F. FOR A PERIOD OF TIME FROM ABOUT TEN HOURS TO ABOUT ONE HOUR, RESPECTIVELY, AND IN THE PRESENCE OF A GAS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN, CARBON MONOXIDE, AND MIXTURES OF HYDROGEN AND CARBON MONOXIDE, THE PARTIAL PRESSURE OF SAID GAS FALLING WITHIN THE RANGE VARYING FROM ABOUT 50 POUNDS PER SQUARE INCH TO ABOUT 5000 POUNDS PER SQUARE INCH. 